This reminds me of an incident I just had last week.  My TV is being repaired, so thought I would watch a DVD on my notebook while I work on my main box.  My notebook is XP home since I had to do work on MFC programs for school awhile back.

Trying to play any dvd would give me the lovely error along the lines, "Windows Media Player can not play this DVD due to Digital Copy Protection."  I thought that was pretty weird.  I had played dvds just fine before, so I tried windvd and it still doesn't work.  Follow the help links to see what could possibly be different and somehow I keep ending up at M$'s site giving me links to spend ~$20 for a dvd decoder program. 

I felt pretty mad being directed to spend more money to watch the dvds that I own.  Needless to say, my notebook is now running FC4 and playing dvds just fine with xine and 'libdvdcss'.